Art of cementation and hardening of metallic objects.



H. NETTGENS.

ART OF CEMENTATION AND HARDENING 0F METALLIC OBJECTS. APPLICATION FILED MAR-3,19I7- Patented Nov. 27, 1917.

2 SHEETSSHEET 1.

H. NETTGENS. ART OF CEMENTATION AND HARDENING 0F METALLIC OBJECTS.

W APPLICATION FILED MAR. 3, I917 lmmfis.

Patented Nov. 2?, 1917,

2 SHEETS-SHEET 2.

till

residing at llerrliberg,

instance common the grate serving I F: GE

NETTGENS, f HEERLHBERG, S'WITZERL.

Application filed march 3,

.To all whom it may camera:

Be it known that T, HEINRICH Nnrrenns, a citizen of the Swiss Confederation, and Switzerland, have invented certain new and useful Improvements in the Art of Cementation and Hardening of Metallic Objects, of which the following is a'specification.

The present invention relates to a novel and improved process for cementing and tempering metal objects and to an oven for carrying out this process. I

Accordingto this rocess a layerof substances, which at t e required voperative temperaturesfuse and vaporize, such as for salt, potassium nitrate, barium carbonate, ammoniacal salt, lead and. the like, is introduced into the hardening chamber of the oven, layer, but separated therefrom" in suitable manner, for instance by a grate, is placed the charge or cement layer of bones, leather, carbon and the like, in which the objects to be treated are embedded. The cement bed is then preferably covered over layer containing iron and silica.

The oven for carrying out this process shows a box surrounded by the heat passages and provided with a grate above its bottom, the relatively limited space below.

to receive fusible and vaporizable substances, and the grate itself supporting the cement bed containing the articles to be carburized.

In order to make m invention more readily understood, ll wil now describe it in detail with reference to the accompanying drawings, in which it" 1 represents a vertical section thro g an oven well adap for carrying out my new process; Fig. 2 shows a through, on line A-'-B of Fig. 1, looking downwardly; Fig. 3 represe ts a vertical section through the Fig. 1, looking by a top toward the right; Fig. 4i shows a vertical section through the charge case, and Fig. 5 shows a fragmental plan view thereof.

e oven is constructed well hown manner of rehactery mate, preferably Specification of Letters Patent;

and above this the layer of horizontal section, there.

even on line (3-D of Patented Nov. ht, 191W.

ierr. Seria11to.152,$14l.

chamot-te brick, and essentially comprises the burner chambers 8, the hardening chamber 1, and the pro-heating chamber 2, vented by chimney 3. Any suitable heating medium may be employed, but I. prefer to use crude oil, which is conducted to the spraying nozzles 4 through the feed pipes 5, and into which is forced pressure air through the pipes 6. The several pipes 5 and 6 are provided with the usual controlling devices, not specially shown here, and each spray-nozzle is controlled by a needle valve 7, as well known in the art. Deflectors are arranged in the path of the fuel jet.

The fuel nozzles operate in oppositely disposed; gradually widening chambers 8, two nozzles being arranged for example on one side of the oven, and one between these two on the opposite side. The burner chambers 8 communicate with the pre-heating chamber 2 by the ascending dues or passages 9, which open into the chamber 2 Just above its bottom level. The working chamher 1 thus is exposed all around to the action The heat passages. 9

causes a damming-up or low the chamber 1.

Into the hardening chamber 1 is horizontally built-in a lidless case or tray l1 which supports on its bottom 11' a grate made up of a plurality of adjacently disposed parallel bars 12, which rest loosely on cross-members l3 and form between one another narrow interspaces 12', as shown in Figs. d and 5.

The horizontal partition wall it between the chambers 1 and 2 is provided with va or vents 14, and the two chambers are close. is respectively by doors 16 and 17 For the cementation of iron and steel ebjects the operation of the oven is the following :-The oven is preheated by partly opening the fuel nozzles. lUpon'the grate is then placed a layer of substances such as above indicated, which will readily melt under the pre-heat and then flow downwardly through (ill (ill

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' articles under 56 the grate interspaces 12 onto the case bottom where they form a heat-storing layer 18 (Fig. 4). Next a layer 19 of carbonaceous and nitrogenous substances, such as bone, leather scraps, carbon and the like, is placed on the grate, into WhlCh then the articles 20 to be treated are embedded. Finally, a thin cover layer 21 containing iron and silicate is superimposed upon the cement bed, which cover layer may, for instance, consist of a mixture of iron filmgs, glass in powder form, and sand.

The doors 16 and 17 the fuel atomizers are fully opened. The heating gases pass through the passages 8, 9 and 10 into the chamber 2 and finally out through the vent 8. In their course, cially by their being dammed-up, as described, the gases heat the tempering chamber to such an extent that the lowermost layer below the grate is brought up to a temperature of, say, 1100 celsius, while above the grate the temperature registers only between 800900 th The substances below t vapors which will partly and with it the epending upon the choice of the substances used, so that oxidation of the articles under treatment is prevented. The bone and leather carbonize and the thus freed nitrogen facilitatesthe penetration of the carbon molecules. The vapors passing up between the grate bars favorably'influence the tempering process and tend to keep the carbon loosened-up. The glass, and the sand cake with the iron filin and together form an elastic covering, be ow which no oxygen reniains, so that decarburization cannot take p ace.

The mass below the grate serves as heat accumulator and distributer and imparts as such an-even heat to all parts of fter the first charge has thus been cemented, it is readily exchanged for a fresh one which has preferably been pro-heated in the chamber 2. The entire operation res grate generate drive out the air filllrGS considerably less time and fuel than 50 eretof for instance, heating-up the chamber 1 for 3 hours at a temperature of between 800 and 900- celsius shows on the treatment a hardened layer or skin of 14% millimeter in thiclmess, which in prior methods and ovens was obtained only after 10 and more hours, under otherwise equal conditions.

For the reason that the treated articles are in immediate contact with and the vapors, w

oxygen, and partly absorb it,

are now closed and P espeoccur. The 0th cles can readily be hammered without scalmgr ofi'.

he described process can also be used for ardemng 11011,

e obtained by-the use of a der or other and the like.

Neither the bedded therein the heating could also be bviously, also any other suitable heating medium may be used in place of the liquid fuel here described.

ver the now used cementing processes with their hermetically sealed cases,

hardening powmeans, such as lead, salt baths cement nor the articles emmedium. The lower layer e may be removed by itself at any time uring the full operation of the oven, since no undesirable oxidation by air-oxy en can er articles, on the so he extracted article at once becomes covered by vapor deposit with an extremely thin oxidation-preventing protective cover.

he oven is well adapted for continuous operation. I

V at I claim is 1. The described cementing ing process, which consists in introducing into the hardening chamber of the oven a layer of substances adapted to fuse and vaporize at the operative temperatures, and arranging above this said layer, but not in direct contact therewith, the cementin layer which is to receive the articles to be treated. .2.- The described cementing and hardenng process, which consists in introducing and hardenmto the hardening chamber a. layer of'sub-- stances adapted to o ing layer a cover layer containing iron and silicate. U

3. In an oven for cementing and hardening, including a housing and heatin means therefor, a case arranged within said hous gig and adapted to receive a layer of subances fusible and vaporizable at the operathe cementin ed and tobetrea temperatures and containing the articles come into direct contact with I poured-in in pre-liquefied state.

means in said case for preventing the said menting bed for the articles to be treated fusible and vaporizable layer from coming andmeans in said case-for preventing said 10) into direct contact with said cementing bed. fusible and vaporizable 1a er from coming 4. In an oven for cementing and hardeninto direct contact with said cementing bed 5 ing, including a housing and heating means consisting of a perforated grate in the botthereior, a case arranged within said houstom of said case.

ing and adapted to receive a layer of fusible and vaporizable substances and the 012- HEINRIGH NETTGENS. 

